What do you want to do with it? Hunt? Target? Self Defense? "Survival"? If the latter, I suggest the S&W Military and Police revolver in .357 Mag - Model 13, IIRC. Utterly simple, long lived and reliable with enough power to take almost any animal on the continent. Being a revolver, it has no magazine to loose or bugger up. Fixed sights mean there is nothing to get knocked out of alignment, and if the shooter does his part, can place shots accurately at any handgun distance. The K Frame Smith also has many accessories available from target hammers and triggers to natural wood or rubber oversized grips, which greatly increase shootability and recoil control.
Regarding self defense, the key element in any defensive firearm is reliability. Being strictly mechanical, a quality revolver such as the M-10 / 13 cannot help but be more reliable than any autoloader which is dependent on magazine condition, tightness of hold, spring condition, etc. I have seen some pretty beat up K frames in my shooting days, but I have never seen one which failed to function when needed. Power? Even the .38 Special in its mildest loading is nothing you'd want to stand in front of. In .357 Mag., if the bullet didn't get you, the report and muzzle flash will.
For hunting and target work, the M&P is limited by a 4" barrel - it may not be legal to hunt with in some states, and most target revolvers have at least 6" barrels. If this is an issue, look at the Combat Magnum (M-19) in a 6" barrel, but be prepared to deal with the disadvantages of adjustable sights.
Plus, it's hard to argue with success. This revolver has been in constant production in one form or another for almost 120 years. Despite what the experts
say, no organization or agency will arm its people with a firearm that does not do its job. At least in the USA.
If I could have only one centerfire handgun, it would be an M-10/13.
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